Door latch



April 1959 c. J. M. KOK 2,881,020

DOOR LATCH Filed May 25, 1956 United States Patent DOOR LATCH CornelisJ. M. Kolr, Amsterdam, Netherlands Application May 25, 1956, Serial No.587,355

Claims priority, application Netherlands May 31, 1955 3 Claims. (Cl.292-78) This invention relates to a door latch provided with a bellcrank lever of which one arm, on closing the door, enters into a recessin the door frame with one or more springs acting on the other arm ofthe bell crank lever so as to urge the bell crank lever to swing intothe closed position.

The invention aims at providing a door latch of the said type in suchmanner that its mechanism requires little space and may be accommodatedin a casing adapted to be mounted in a door like a normal lock casing.According to the present invention the bell crank lever arm pointinginwards is connected by a connecting rod to a body guided slidably in arectilinear manner in a lock casing, the spring or springs being fixedto said body. It is preferred to form the slidable body as a cylindercontaining a liquid or a liquid mass, the said cylinder being slidableon a stationary piston provided with one or more passages so as toenable the cylinder to act as a buffer.

In the drawings showing an embodiment of the latch according to theinvention Fig. 1 shows a view of the lock casing with removed coverplate so that the mechanism is visible.

Fig. 2 is a section according to the line H-II in Fig. 1.

The lock casing 1 has a removable cover plate 2 and at the front a plate3 is affixed to the lock casing, said plate 3 serving to secure thecasing in the door 4. On the inner wall of the lock casing two lugs 6are provided in which a pin is inserted around which a bell crank levermay swing, the outwardly projecting arm 7 of the said lever forming alock bolt and the inwardly projecting arm 8 being hingedly connected bymeans of a pivot 19 to two connecting rods 9, said connecting rods 9being hingedly secured to a cylinder 10 which is provided with twodiametrically projecting journals 11. The cylinder is slidable on apiston 20 of which the rod 14 ends in a pin 12 secured in the lock case.The cylinder 10 is filled with a liquid, which when opening or closingthe door, may be transferred in a conventional manner from one side ofthe piston 20 to the other side through passages 21 provided in thepiston.

Two draw springs 13 are fixed to the journals 11, the other end of eachspring being attached to the lugs 6, these springs keeping the lock bolt7 in the position shown in Fig. 2 when the door is open.

The lock bolt 7 co-operates with the wall 15 of a recess provided in thedoor frame 16. On closing the door the nose 17 of the lock bolt abutsagainst the Wall 15 of the recess in the door frame due to which the arm8 shown in Fig. 2 swings through its dead centre position so that thesprings 13 cause the lock bolt 7 to swing outwards 2,881,020 PatentedApr. 7, 9

ICC

until the door comes to rest against the groove 18 in the door frame,the nose 17 of the lock bolt being closed in between the opposite wallsof the recess in the door frame. The springs 13 keep the door in thisclosed position. This closing movement of the door is dampened in thatthe liquid in the cylinder 10 is caused to flow from one side of thepiston to the other side.

As appears from Fig. 2, the cylinder 10 is guided not only on thestationary piston but also between the walls of the lock casing thusensuring a satisfactory guiding.

I claim:

1. A door latch provided with a casing, a bell crank lever swingablymounted in said casing, one arm of said lever projecting from saidcasing, a spring mounted in said casing and cooperatively engaged withthe other arm of the bell crank lever for urging said lever to swinginto the closed position, said first arm of the bell crank lever forminga lock bolt and having a head provided with cutaway portions and lying,in the open position of the door latch, against the outer side of thecasing and cooperating with a recess in a door post of a door betweentwo positions lying at both sides of a dead center line of the bellcrank lever, said cut-away portions of said head being arranged so thatsaid head may pass one wall portion of said recess and may abut againstanother wall portion of said recess whereby when said head abuts againstthe last-mentioned wall portion, the bell crank lever will swing throughits dead center line position and said head will cooperate with thefirst-mentioned wall portion for closing the door.

2. A door latch provided with a casing, a pin mounted in said casing, abell crank lever swingably mounted on said pin, one arm of said leverforming a lock bolt and projecting from said casing, a body slidablyguided in a rectilinear manner in the lock casing, two springs eachhaving one of their ends secured to said slidable body and their otherend fixed on the casing, said body having oppositely extending lateraljournals, and rods pivotally connecting the other arm to said journals,said lock bolt having a head provided with cut-away portions and lying,in the open position of the door latch, against the outer side of thecasing and being destined for cooperating with a recess in a door postof a door between two positions lying at both sides of a dead centerline of the bell crank lever, said cut-away portions of said head beingarranged in such a way that said head may pass one Wall portion of saidrecess and may abut against another wall portion of said recess so thatwhen said head abuts against the lastmentioned wall portion the bellcrank lever will swing through its dead center line position and saidhead will cooperate with the first-mentioned Wall portion for closingthe door.

3. A door latch according to claim 2, characterized in that the slidablebody is formed as a cylinder containing liquid, said cylinder beingslidable on a piston secured in the casing and provided with one or morepassages.

References Cited in the file of this patent UNITED STATES PATENTS2,389,056 Jamison Nov. 13, 1945 FOREIGN PATENTS 18,261 Australia Jan. 3,1935 243,625 Germany Feb. 20, 1912

